Drill bit



y 18, 1939, v R. N. RIBLET 2,156,478

DRILL BIT Filed May 22, 1937 RQg /IKAfA/d 3nnentor attorney Patented July 18, 1939 PATENT OFFICE DRILL BIT Royal N. Riblet, Spokane, ,Wash assignmof one-half to Hugh Harlow, .Ir., Tacoma, Wash.

Application Mayzz, 1937, Serial No. 144,269

1 Claim.

My present invention relates to drill bits of the impact type, which bit, while adapted for use in various ways, is especially designed for drilling blasting holes employed in different forms of excavation work and especially for hard rock drilling in mines or other places.

The primary object of the invention is the provision of a high speed drilling bit in which the cutting members are arranged in such manner as to insure maximum durability for the cutters with which the face of the bit is studded and also to insure maximum eiiiciency for the bit in the performance of its functions of earth drilling or' boring. The invention consists essentially in certain novel combinations and arrangements involving a bit having a shank for attachment to the chuck of the usual type of pneumatic, im"act drilling equipment or any other form of machine which,

through a series of rapid blows, presents the cutters of the bit against the material operated on to fractionate or reduce the rock or materal to a fineness. 1

Such drill shanks are provided with water holes through which water may be forced to wash away the cuttings reduced by the cutter members on the face of the bit and the cutters are arranged in such a manner that they may be replaced at required intervals and the entire drill bit renewed for continued work without the necessity ofreturning all of the steel to the blacksmith or tool sharpener, which in most drilling operations requires the double handling of tons of drill steel in order to sharpen the faces of the bits accompanying the steel.

In the accompanying drawing I have illustrated several forms of the invention in which the bit is adapted for work in both hard and soft earth 0 where excavations are to be made, in mines where ore bodies are encountered and u'sually surrounded by extremely hard rock, in tunnel work, and in all other forms of drilling operations.

It is to be understood that changes and alterations may be made in these exemplifying structures within the scope of my claim without departing from the spirit of my invention.

Figure 1 is a side view of a bit employing my invention disclosing the shank portion of the o usual form of drill bit and showing the removable cutters in the working face of the bit.

Figure 2 is an enlarged and view of the drilling Figures 4 and 5are modified forms of my bit, as disclosed in Figure 2.

Figure 6 is a perspective of one of the cutters and Figure 7 is an elevation showing the reduced cutter faces of the group of four successive cutter 5 members.

In the form of the invention shown in Figures 1 and '2 the bit I0 is adapted for boring or drilling in hard rock, granite, and other hard materals, though it is not confined iiiany sense to particul0 larly hard rock 'or earth, but is intended for all purpose drilling.

In Figures 1 and 2 four radially mounted replace'able cutters I, 2 l ,l,are illustrated, and in Figure 4 cutters ls, 2a,.3a, la are utilized in 15 the face of the .bit and held in position by means of soft rivets I! which areeasily removable when occasion demands and which will insure that the cutter members will be held substantially. to the bit head l0 forming the supporting means for the 20 cutters. -The cutter members are fitted into grooves l3 cut into the head l0 and in the case of the structure disclosedin Figure 2 each cutter provides a stop or gauging means for the adjacent cutter on one side. This is repeated until all 25 cutter members are in contact with each other to form an accurate gauge for the hole being drilled. .The rivets I! are intended to be loosely fitted into holes II in the replaceable cutter members so'that they serve for the most part as retainers so and not as gauge means for the drilling. The true gauging means as in Figure2 is provided by forming each cutter member with a slightly bevelled face I} on its inner eniwl'iich provides an overlap for one adjacent cutter member and serves 35 as a stop for that cutter member forming a somewhat square hole at the function points of the .cutters, this hole being-su mcient to permit the vflow of water through the shank of the drill and out and around the cutters to wash away the cut- 40 tings removed by the cutters. Another feature of the bit consists in the formation of the cutting faces of the cutters. These edge at I, cutters I and 3a are likewise cut back an increased lractional part of the cutting edge;

cutters 4 audio are reduced .to approximately one-halter the cutting face in a like manner. While there are fourcutters to make up a set of my each one being identical except for the width of the cutting face, one operation for forming these members is to grind away a portion of the edge before the cutters are tempered. Other forms and means may be used to accomplish this purpose.

With the drill bit thus mounted with replaceable cutters more rapid drilling is possible and with the assurance of greater clearance for the cuttings or particles removed from the face of the hole. This permits the flow of water to more rapidly pass the particles away from the bit and the chief object accomplished in such a bit as I have herein described is to provide cutting edges that will beequalized in the area of the hole in this manner. The exact center of the bit has little or no travel as the bit rotates during its operation. The cutting edges on the periphery or outside of the 'bit travel the maximum distance or a distance equal to the circumference of the-circle of the bore. Thus in a two-inch bit the outer edge of the cutting face in one revolution of the bit will have travelled slightly more than six inches. A point intermediate between the center and the extreme outer edge of the-cutter will travel slightly more than three inches. The cutter edge at the hole of the bit which is approximately one-quarter inch will travel approximately three-quarters of an inch in one revolution. Hithertofore bits have been made with all the cutting edges reaching from the central or water hole to the outside or gauge of the tool. Y

In my construction I eliminate the interior edges of the cutters and substantially equalize the work performed by the cutters over the area of the cut or bore of the hole. Thus all cutters have cutting-edges from the gauge point inward and each of the cutters, with the exception of one, has the cutting edge reduced to secure this equalization. In this manner the cuttingedges will not be utilized over a part of the surface for grindin up the cuttings after being removed from t e rock face resulting in lessened power and increased rapidity of In Figure 2 I have disclosed means whereby my bit may be manufactured by milling or forming two right angular channels across the face of the bit III to receive the cutters. I have provided holes in the wings of the head to receive a soft rivet which may be readily driven out by proper tools when new or renewed cutters are to be inserted. 4

In Figure 4 I have shown a somewhat different structure in that the slots or grooves II are formed with an end miller which when it has of my invention being disclosed at 2|.

reached its innermost point will leave a curved end or abutment. The cutters in, 2a, 3a, la

are also formed with a semi-circular or inner end I; and abutting upon the abutment I! to establish the desired gauge 'for the drill bit.

Figure 5 is formed in the same manner as the bit of Figure 2 but the cutter members II have their cutting faces of equal length and their abutting ends formed at a slight angle to insure the establishment of a fixed gauge for the cutters and the consequent hole to be drilled. 7

By reference to Figure 6 showing a perspective of one of the series of cutter members, the cutting edge is indicated at 20, the cut-away portion for clearance and for establishing the principle The hole I for receiving a rivetand a cut-out portion 22 is established on the inner end of the cutter to insure maximum clearance for water as it passes from the water hole or channel through the drill shank. All of the cutters, in a set are formed identical except that the length of the cutting edge 20 is altered to insure that the hole willbe presented evenly with cutting faces in accordance with its diameter to insure that the material is cut from the face of the hole and-not re-cut or ground during the operation -of the drill, thus allowing rapid removal of the cuttings as wellas rapid progress in the drilling operation. While I have described in the drawing of my invention a drill bit in one piece with the shank portion of a drill rod I also contemplate the making of my bit in a short length or head which may be secured to a drill rod through the use of threads or any suitable means for joining the short bit section to such a rod.

Having thus ru11 described my invention, what I claim as new and desire to secure by Letters Patent is:

The combination with a tubular drill rod having an integral open center head comprising two sets of transversely extending radially-grooved wings having transverse holes therein, of a series of cutters fitted in said wings and having holes registering with the wing-holes, readily remov-.

able soft-metal rivets secured in the complementary wing-holesand cutter holes, each said cutter having a transversely extending beveled inner end with its edge overlapping an adjoining groove and forming a gage-abutment for another cutter, one of said cutters having a full-length cutting edge, and the remaining cutters having cutting edges of decreasing length.

ROYAL N. RIBLET. 

